1,721,001 research outputs found
Composición isotópica de ácidos grasos en suelos agrícolas mediterráneos con rotación trigo (C3)-Maíz (C4) y la incorporación de los residuos de cosecha
No full text5 páginas.- 3 figuras. 4 referenciasLos lípidos del suelo son sustancias de origen vegetal o microbiano, insolubles en agua y solubles en disolventes orgánicos. Esta fracción orgánica incluye biomarcadores asociados a diferentes comunidades microbianas y proporciona información sobre la dinámica de la materia orgánica del suelo (MOS) y de los intercambios de carbono. En este trabajo presentamos los resultados preliminares obtenidos en un experimento de marcaje isotópico natural en un suelo agrícola mediterráneo de la estación experimental "La Hampa" (Sevilla), sometido a rotación de cultivos trigo (C3)-maíz (C4). La fracción lipídica del suelo se estudia a distintas profundidades mediante cromatografía de gases acoplada a espectrometría de masas (GC-MS) y su composición isotópica de carbono (δ13C) se determinó en compuestos los años de cambio a cultivo de maíz y de aportes de su biomasa al suelo, se encontró un enriquecimiento significativo de δ13C (c. 2 ‰) para los FAME saturados C20, C22 y C23 y el monoinsaturado FAME C22:1 y de hasta 5 ‰ en alcanos C29 y C31. No se encontraron diferencias significativas para los alcoholes e hidroxiácidos. Estos cambios isotópicos pueden deberse a una mayor especificidad de los alcanos de cadena larga de origen vegetal, mientras que los otros compuestos son menos específicos y pueden tener un origen diverso. No se observaron diferencias significativas en la composición isotópica de la MOS a las diferentes profundidades del suelo dentro de un mismo tratamiento. Todo ello, junto al bajo contenido en materia orgánica (MO) que se mantiene constante a pesar de la cantidad de biomasa C4 agregada durante el cultivo, apunta a altas tasas de mineralización y a una rápida transformación de los restos vegetales en estos suelos agrícolas mediterráneos.Se agradece al MINECO y al Fondo Europeo de Desarrollo Regional (FEDER) la financiación del proyecto CGL2016-78937-R. A Desiré Monis Carrere por la asistencia técnica en laboratorioN
Changes in nutrient contents in peel, pulp, and seed of cherimoya (Annona cherimola Mill.) in relation to organic mulching on the Andalusian tropical coast (Spain)
No full text7 páginas.- 4 figruas. 5 tablas.- 32 referencias.- Supplementary material related to this article can be found, in the
online version, at doi:https://doi.org/10.1016/j.scienta.2019.109120Cherimoya, a tropical fruit from South America whose commercial demand is increasing for both its exceptional flavor and high nutritional content, is expanding in cultivation to subtropical areas such as the Mediterranean coast of Andalusia (Spain). In this paper, we analyze cherimoyas (peel, pulp, and seed) grown in Almunecar (Granada, Spain) during the years 2013, 2015, and 2016 from trees applied with different pruning wastes (avocado, cherimoya, mango, and garden). The cherimoya fruits had high contents in most of the macronutrients, especially K, Ca, and micronutrients such as Fe and Zn. The Na, P, K and Ca concentrations were related to the plant mulch that released nutrients to the soil and led to a variation in soil-nutrient bioavailability by decreasing the soil pH. The seed was the part of the cherimoya that registered the least nutritional change due to annual weather differences and the highest positive effects of mulching in terms of increased nutrient availability after mulching.Authors appreciate the financial support of this work by the Spanish Ministry of Economy and Competitiveness (Project CGL-2013-46665-R) and the European Regional Development Fund (ERDF).Peer reviewe
Análisis isotópico directo de compuestos específicos mediante pirólisis (PY-CSIA) de corteza y lignina: obtención de biomarcadores
No full text16 diapositivas de la presentación en el Ciclo de conferencias predoctorales 2019 del IRNASN
Pyrolysis-compound specific isotope analysis (Py-CSIA) of polymers and biopolymers: possible applications in heritage conservation.
No full textPóster presentado en EGU 2019, Viena (Austria) 7 al 12 de abril de 2019. Puede ver el Abstract en https://meetingorganizer.copernicus.org/EGU2019/EGU2019-17062.pdfGiven the artistic, social and economic value of cultural heritage, its conservation is of upmost importance for being preserved for future generations. Through accurate characterization of organic materials, such as alteration products and biopolymers used in the past as construction, supporting or protective materials of in monuments
and artistic artifacts, it would be possible to ameliorate the conservation practices for controlling deterioration. Pyrolysis-compound specific isotope analysis (Py-CSIA) is a novel analytical technique able to provide, not only an accurate identification of organic compounds in different complex matrices, but also additional valuable information about nature and origin of the materials based on their isotopic composition. This technique is based on the coupling of a micro-furnace pyrolyser (F.Lab 3030i) to a gas chromatograph (GC) and using an isotope ratio mass spectrometer (IRMS) as detector. The individual volatile pyrolysis products separated by gas chromatography are directed to a combustion or a pyrolysis micro-reactor (GC-Isolink system) and finally the isotope composition of the gases produced measured in the IRMS (Thermo Fisher Delta V Advantage) via an appropriate interface (ConFlo IV universal interface unit). With this technique it is possible to make direct measures of stable isotope ratios (i.e. [U+1D6FF]13C, [U+1D6FF]D, , [U+1D6FF]15N and also [U+1D6FF]18O) of specific compounds with minimum sample handling. In this communication we will introduce the Py-CSIA technique in the field of cultural heritage as a novel technique for the direct determination of the isotopic composition of polymers and biopolymers. Case studies on
the characterization of biopolymers using Py-CSIA will be presented and the potential application in the field of cultural heritage conservation discussed.[1] González‐Pérez et al. (2016). Compound‐specific stable carbon isotopic signature of carbohydrate pyrolysis products from C3 and C4 plants. Journal of the Science of Food and Agriculture, 96(3), 948-953.
[2] González-Pérez et al.. (2015). Pyrolysis-gas chromatography–isotope ratio mass spectrometry of polyethylene. Journal of Chromatography A, 1388, 236-243.
[3] Gil et al. (2011). Stable isotopes and human diet in central western Argentina. Journal of Archaeological Science, 38(7), 1395-1404.
[4] Mottram et al.. (1999). New chromatographic, mass spectrometric and stable isotope approaches to the classification of degraded animal fats preserved in archaeological pottery. Journal of Chromatography A, 833(2), 209-221.
[5] Tambakopoulos, D., & Maniatis, Y. (2017). The marble of the Cyclades and its use in the Early Bronze Age. Early cycladic sculpture in context. Oxbow: Oxford and Philadelphia, 468-82.
[6] von Holstein, I. C., & Makarewicz, C. A. (2016). Geographical variability in northern European sheep wool isotopic composition (δ13C, δ15N, δ2H values). Rapid Communications in Mass Spectrometry, 30(12), 1423-1434.This research has been funded by the Spanish Gov. ‘Ministerio de Ciencia , Innovación y Universidades’ under grant ref. BES–2017–079811 . Project CGL 2016 -78937 –Co-financed by FEDER Funds .N
Direct compound specific isotope analysis (δ2H, δ13C) of biomass components using analytical pyrolysis (Py-CSIA)
No full textComunicación oral presentada en el 1st Iberian Meeting in Separation Sciences & Mass Spectrometry, XIX Conference of the Spanish Society of Chromatography and Related Techniques (SECyTA), IX Conference of the Spanish Society of Mass Spectrometry (SEEM), VI Conference of the Mass Spectrometry Group of the Portuguese Society of Chemistry (SPQ). Santiago de Compostela, October 8th-11th (2019).-Changes in climatic and environmental conditions can affect both, plant chemical and isotope composition. Nowadays, many studies use bulk isotope values, which represent a weighed mean average of the different plant compounds. An isotopic characterization of individual biogeochemical compounds is desirable in order to differentiate the isotopic composition of the main plant components. However, biomass is composed mainly of high MW biopolymers i.e. polysaccharides (celluloses), polypeptides (lignin), polypeptides (proteins), polyesters (waxes), etc. not amenable to most chromatographic techniques without the use of more or less previous intense extraction and sample preparation.
Here, a particular analytical pyrolysis technique combining Py‐GC with a continuous flow isotope ratio mass spectrometer (IRMS) (Py‐CSIA) is described and validated. Isotopic values obtained by Py‐CSIA of standard n‐alkanes mixtures (dissolved C16 to C30 series with increasing concentrations along three pentads, Indiana Univ. SIL mix. Type B), fitted well to a straight line (R2 > 0.999). No induced thermal cracking nor deviations from the acclaimed isotope composition (fractionation) was observed up to high pyrolysis temperature (< 400 °C). Results linking detailed molecular and isotope composition obtained by the direct analysis of various biomass types and biopolymers will be discussed. In general, our results show that Py‐ CSIA can reveal major differences between biomass components from different biogenic origin with high precision. In addition, despite that biomass pyrolysates from different origins may yield very similar Py‐GC/MS patterns, Py‐CSIA can make the difference providing additional valuable isotopic information.Ministerio de Ciencia Innovación y Universidades” INTERCARBON project (CGL2016‐78937‐R). N.T. Jiménez‐Morillo and L. San Emeterio thanks the MICIU for funding FPI research grants (BES‐2013‐062573 and Ref. BES‐2017‐07968). Desiré Monis is acknowledged for technical assistancePeer reviewe
Reuse of pruning waste from subtropical fruit trees and urban gardens as a source of nutrients: Changes in the physical, chemical, and biological properties of the soil
No full text10 páginas.- 6 figuras.- 5 tablas.- 49 referenciasA field experiment was conducted on the Andalusian coast (Granada, Southern Spain) to study the time course of nutrient release into the soil after the addition of bagged pruning waste from subtropical orchard trees (avocado, cherimoya, and mango) and urban garden waste over three two-year periods. N, P, and K concentrations were greater in the garden waste, whilst avocado and cherimoya pruning waste registered the highest values for Mg. In general, micronutrient contents were low in all waste, especially Cu. Macronutrient release followed a three-phase dynamic: fast initial release, intermediate stabilization, and final increase. Garden waste showed a similar time course in all three trees and released greater concentrations of K and P. The annual decomposition rate factor k was negative for N and Ca in the avocado tree, indicating strong biological activity in this plot. Avocado, cherimoya, and garden waste showed a good microbial degradation, improving soil quality by increasing carbon and nitrogen contents as well as soil microbial activity. As for the mango tree, its special microclimatic conditions appeared to favor waste photodegradation, thus eliminating nutrients that were not incorporated into the soil. Soil enzymatic activities increased in the avocado and cherimoya trees with the addition of all waste. In the mango tree, only an increase in urease was detected after the addition of garden waste. Our results suggest that the time course of organic waste in different subtropical trees grown on similar soils is significantly conditioned by the microclimatic characteristics. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: Authors appreciate the financial support of this work by the Spanish Ministry of Economy and Competitiveness (Project CGL-2013-46665-R) and the European Regional Development Fund (ERDF).Peer reviewe
Fingerprinting macrophyte Blue Carbon by pyrolysis-GC-compound specific isotope analysis (Py-CSIA)
No full text10 páginas.- 4 figuras.- 1 tablas.- referencias[EN]: There is a need for tools to determine the origin of organic matter (OM) in Blue Carbon Ecosystems (BCE) and marine sediments to (1) facilitate the implementation of Blue Carbon strategies into carbon accounting and crediting schemes and (2) decipher changes in ecosystem condition over decadal to millennial time scales and thus to understand and predict the stability of BCE in a changing world. Pyrolysis-GC-compound specific isotope analysis (Py-CSIA) is applied for the first time in marine environments and BCE research. We studied Australian mangrove, tidal marsh and seagrass sediments, in addition to potential sources of OM (Avicennia, Posidonia, Zostera, Sarcocornia, Ecklonia and Ulva species and seagrass epiphytes), to identify precursors of different biomacromolecule constituents (lignin, polysaccharides and aliphatic structures). Firstly, the link between bulk δ13C and δ13C reconstructed from compound-specific δ13C showed that the pyrolysis approach allows for the isotopic screening of a representative portion of the OM. Secondly, for all samples, the C isotope fingerprint of the carbohydrate products (plant polysaccharides) was the heaviest (13C enriched), followed by lignin and aliphatic products. The differences in δ13C among macromolecules and the overlap in δ13C among putative sources reflect the limitations of bulk δ13C analyses for deciphering OM provenance. Thirdly, phanerogams specimen had the heaviest carbohydrate and lignin, confirming that seagrass-derived lignocellulose can be traced based on δ13C. Consistent differences for individual compounds were identified between seagrasses and between Avicennia and Sarcocornia using Py-CSIA. Fourth, ecosystem shifts (colonization of seagrass habitats by mangrove) on millenary time scales, hypothesized in previous studies on the basis of bulk δ13C and Py-GC–MS, were confirmed by Py-CSIA. We conclude that Py-CSIA is useful in Blue Carbon research to decipher OM sources in marine sediments, identify ecosystem transitions in palaeoenvironmental records, and to understand the role of different OM compounds in Blue Carbon storage.[ES]: Es necesario desarrollar herramientas para determinar el origen de la materia orgánica (MO) en ecosistemas de “Blue Carbon” (BCE) y en sedimentos marinos para (1) facilitar el desarrollo de estrategias de “Blue Carbon” en los esquemas de contabilidad y acreditación de C (2) descifrar cambios en las condiciones del ecosistema a escala de décadas a milenios y, por lo tanto, comprender mejor y predecir la estabilidad de BCE en escenarios de cambio climático. En este trabajo, aplicamos por primera vez el análisis de isótopos estables de C en compuestos específicos liberados por pirolisis (Py-CSIA) en entornos marinos y en la investigación de BCE. Estudiamos sedimentos de manglares, marismas y praderas marinas de Australia, además de las fuentes potenciales de MO (especies de Avicennia, Posidonia, Zostera, Sarcocornia, Ecklonia y Ulva y epífitas de praderas marinas), para identificar precursores de los diferentes constituyentes de las principales biomacromoléculas (lignina, polisacáridos y estructuras alifáticas). En primer lugar, la relación encontrada entre el δ13C total y el reconstruido a partir de los δ13C específicos de los compuestos, indica que el enfoque de pirólisis permite el cribado isotópico de una parte representativa de la MO. En segundo lugar, para todas las muestras, la huella isotópica de C de los productos de carbohidratos (polisacáridos vegetales) fue la más pesada (enriquecida en 13C), seguida de la lignina y los productos alifáticos. Las diferencias en δ13C entre los distintos tipos de macromoléculas y la superposición en δ13C entre las distintas fuentes putativas, pone de manifiesto las limitaciones de los análisis convencionales de δ13C totales (“bulk”) para descifrar la procedencia de la MO. En tercer lugar, las fanerógamas estudiadas mostraron la mayor proporción de carbohidratos y lignina, lo que confirma que la lignocelulosa derivada de pastos marinos se puede rastrear en base al δ13C de compuestos específicos. Mediante la Py-CSIA se identificaron diferencias consistentes para compuestos individuales entre las especies de praderas marinas y entre las de manglar (Avicennia y Sarcocornia). En cuarto lugar, mediante la Py-CSIA de δ13C confirmamos cambios en el ecosistema costero (colonización de hábitats de praderas marinas por manglares) ocurridos en los últimos milenios. Concluimos que la Py-CSIA es útil en la investigación de “Blue Carbon” y para descifrar las distintas fuentes de MO en los sedimentos marinos, identificar transiciones de ecosistemas en registros paleoambientales y para comprender mejor el papel de diferentes compuestos de la MO en el almacenamiento de C en el BCE.O.S. was supported by I+D+i projects RYC2019-027073-I and PIE HOLOCENO 20213AT014 funded by MCIN/AEI/10.13039/501100011033 and FEDER. L.M.S.-E. thanks MINECO pre-doctoral FPI fellowship BES-2017-079811 and J.A.G.-P. project PAIDI2020, PY20_01073. Both projects co-funded with EU FEDER funds. The laboratory personnel Alba M. Carmona and Desiré Monis are acknowledged for technical assistance. We are grateful to the anonymous reviewers for their effort and comments.Peer reviewe
Efectos del cambio climático en la estructura molecular de la materia orgánica del suelo de una dehesa
No full text4 páginas.- 3 figuras.- 7 referencias.- Descripción y Póster nº 46 presentado en el IX Congresso Ibérico das Ciências do Solo (CICS 2022) “O solo, recurso estratégico para uma sociedade sustentável” 22 a 24 de junho de 2022Las sabanas mediterráneas (dehesas) son sistemas agrosilvopastoriles típicos, caracterizados por la presencia dispersa de robles (Quercus spp.) y especies arbustivas. Estos ecosistemas están sometidos a una marcada estacionalidad, propia del clima mediterráneo, lo que se refleja en la dinámica microbiana del suelo. La interacción de los factores que más afectan la dinámica microbiana (clima, vegetación y suelo), es clave para comprender los ciclos biogeoquímicos que, a su vez se espera que se reflejen en la estructura de la materia orgánica (MOS). Para evaluar el efecto del cambio climático, utilizamos pirólisis analítica (Py-GC/MS) para la caracterización molecular de la MOS en un experimento de imitación en campo (2017-2021). Entre los 117 compuestos biogénicos encontrados, las distribuciones y contenidos de ác. grasos y n-alcanos fueron más sensibles a los tratamientos climáticos. Además, se observa una degradación preferencial de compuestos derivados de holocelulosa y acumulación de compuestos derivados de la lignina, que se encuentra poco evolucionada, lo que apunta a condiciones desfavorables para la su degradación. Los resultados sugieren que la composición molecular de la MOS y la aplicación de Py-GC/MS aporta información sobre los cambios ambientales del suelo y que tienen valor como biomarcadores para el seguimiento del cambio climático en suelos mediterráneos.Proyectos EU-EJC 2a Conv. MIXROOT-C., Ministerio de Ciencia Innovación y Universidades (MICIU) INTERCARBON (CGL2016-78937-R) y DECAFUN (CGL2015-70123-R). L. San Emeterio agradece al MICIU por su contrato de investigación FPI (BES-2017-07968). D. Monis, A.M. Carmona y E. Gutiérrez por su asistencia técnicaN
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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